In a plasma gas jetting device described in PTL 1, the periphery of an ejection port for plasma gas is covered by a shielding material, and the ejection port for inert gas is provided externally to the shielding material. Inert gas is jetted prior to and after jetting of the plasma gas on a treatment target object, and thereby, it is possible to improve plasma treatment effects. In addition, since inert gas is ejected on the periphery of the plasma gas, it is possible to make it difficult for the plasma gas to contact oxygen in the air.
In a plasma gas jetting device described in PTL 2, an ejection port for inert gas is provided externally to an ejection port for plasma gas, but an exhaust gas recovery passage is provided between the ejection port for plasma gas and the ejection port for inert gas. Exhaust gas and the like that is generated in plasma treatment is recovered through the exhaust gas recovery passage, but since inert gas is ejected externally to the exhaust gas recovery passage, emission of exhaust gas in the air is favorably suppressed.
PTL 3 describes a plasma treatment system that is connected to multiple plasma treatment devices using connecting sections. In the plasma treatment system, an air curtain is formed by supplying inert gas to respective connecting sections, and plasma treatment spaces partition each of the multiple plasma treatment devices.